Up to half the women in the U.S. experience female pelvic floor disorders (FPFD): stress urinary incontinence (SUI), fecal incontinence, and pelvic organ prolapse (POP). These conditions share common risk factors, including vaginal delivery, and therefore ought to be studied together. The lifetime risk of surgery for FPFD is 11%, with a re-operation rate of 29%. Since age, diabetes, and obesity are risk factors for FPFD, the aging US population and increasing prevalence of obesity and diabetes portend an FPFD epidemic in the U.S. in the coming decades. Female reproductive organs and the pelvic floor are rich in elastic fibers and undergo massive remodeling during pregnancy and childbirth. Lysyl oxidase-like 1 (LOXL1) is a protein essential for elastin remodeling and homeostasis. Unlike in normal mice, vaginal delivery in LOXL1 knockout (KO) mice results in POP and SUI, making it an ideal animal model of FPFD. Stem cells participate in normal repair processes and have the potential to be harnessed as a preventative therapy to facilitate repair after childbirth. We have preliminary data demonstrating that stem cells increase the elastin content of lower urinary tract tissues, suggesting the feasibility of stem cell administration to facilitate recovery after delivery and prevent FPFD. Cytokine gradients produced by injured tissues attract or home circulating stem cells to sites of injury, where they facilitate repair. Since the injuries that cause FPFD are too diffuse to be amenable to direct stem cell injection therapy, stem cell homing could be utilized to provide a viable therapy to facilitate repair after delivery and prevent FPFD. Recent research has demonstrated that stem cells can facilitate repair after injury by secreting paracrine-acting proteins such as growth factors. Identification of these factors may provide a viable noncellular therapy to facilitate repair after childbirth and prevent FPFD. We will utilize the LOXL1 KO mouse model to study if a cellular or noncellular stem cell-based reparative therapy could be utilized to prevent FPFD. The hypothesis to be tested in this project is that mesenchymal stem cells home to pelvic organs after delivery, facilitate recovery, and prevent resultant FPFD via secretion of paracrine factors. This hypothesis will be tested with the following Specific Aims: SA1. Determine the time course over which cytokines involved in stem cell homing and tissue repair are upregulated by the genitourinary organs after vaginal delivery or C-section delivery in LOXL1 KO mice. We will screen for upregulation of potential stem cell homing cytokines with a chemokine/chemokine receptor array system. Confirmation and localization will be made using RT-PCR and immunohistochemistry. SA2. Optimize the dose and timing of MSCs to best facilitate recovery from the maternal pelvic injuries of delivery and prevent FPFD. Fluorescently labeled MSCs will be infused at several time points after pup delivery in female LOXL1 KO mice. Outcomes will include staging of POP, urodynamics, quantitative histological morphometry assessment of elastin amount and pattern of clustering in genitourinary organs. SA3. Determine the receptor-mediated mechanisms of MSC homing & accelerated functional recovery from vaginal delivery. Female LOXL1 KO mice will undergo vaginal delivery and will receive an infusion of MSCs in which homing cytokine receptors have been knocked down via transfection with small interfering RNA (siRNA). The dose and time point of MSC infusion after vaginal delivery identified as most effective in SA2 will be used for the experiments of SA3. Outcomes of SA3 will be the same as in SA2. SA4. Determine the noncellular mechanisms of accelerated functional recovery from vaginal delivery. Infusion of MSCs will be compared to injection of concentrated conditioned media (CCM) from these stem cells. We will utilize both MSCs and CCM of MSCs generated from wild type and LOXL1 KO mice. We will also use siRNA to knock down secreted paracrine factors in MSCs and utilize both the MSCs and CCM from these cells. The dose and time point of MSC infusion after vaginal delivery identified as most effective in SA2 will be used for the experiments of SA4. Outcomes of SA4 will be the same as in SA2 & SA3. Significance. The maternal injuries of childbirth are diffuse and involve injury to many small structures, such as pelvic floor fascia as well as pelvic organs, making direct injection stem cell therapy to all these sites impossible. Therefore, therapies based on stem cell homing or on the systemic effects of stem cells may provide a viable method to facilitate repair of injured tissues and prevent FPFD. In addition, identification of the paracrine factors produced by stem cells and introduction of these factors after delivery may provide a viable noncellular reparative therapy to prevent FPFD. Thus, this research is highly innovative and is of high significance for FPFD.